An oxyalkylene polymer having hydrolyzable silicon groups at molecular terminals, has moisture-curable properties, and it is used for applications as e.g. a covering composition and a sealing composition, by exploiting a characteristic such that the cured product has rubber elasticity.
As the above hydrolyzable silicon groups, groups selected from the group consisting of methyl dimethoxysilyl groups and trimethoxysilyl groups, are usually used.
Among such oxyalkylene polymers having hydrolyzable silicon groups, when a polymer having a methyldimethoxysilyl groups as hydrolyzable silicon groups, was used for a room-temperature-curable composition, a cured product obtained by curing the composition had elongation and flexibility, but there was a problem such that the curing rate of the curable composition was not sufficient when a high curing rate was needed (For example, Patent Document 1).
It is known that with respect to a polymer having trimethoxysilyl groups as hydrolyzable groups, the trimethoxysilyl groups tend to be easily hydrolyzed, and cross-links by siloxane bonds tend to be easily formed, whereby it is possible to provide an elastic body by quick curing, in the presence of moisture (For example, Patent Document 2 or 3).
However, when the polymer having trimethoxysilyl groups was used alone, a curable composition to be obtained usually had a remarkably high curing rate even at room temperature (for example, 23° C.), whereby it tended to be difficult to secure working time.
In the above case, in order to have a high strength, it is common to use a method of using a polyoxyalkylene having at least one hydrolyzable silicon group in one molecule obtained by using a polyoxypropylene triol as a raw material. However, in such a case, a high strength may be obtained, but there were limits in the elongation and elastic modulus after curing by moisture.
Patent Document 1: JP-B-58-10418
Patent Document 2: JP-A-3-47825 (EP372561)
Patent Document 3: JP-A-10-245484